1. Field of the Invention
The present invention relates to the field of methods for automatically programming radio-television signal receivers; more in particular, it relates to a device and a method for automatically programming a receiver adapted to receive radio-television signals in at least two different formats.
2. Present State of the Art
During the transition, or switchover, from analog to digital television, analog television will be gradually suppressed. During this transition phase, which according to the European Union's plans will end in 2012 in Europe, all television stations will cease broadcasting in analog format and will have to broadcast exclusively in digital format. The transition of a given program from analog to digital occurs in a rather abrupt manner. A television station will suddenly stop broadcasting in analog format in a certain channel and will start broadcasting in digital format in the same channel previously occupied by the analog station or in another channel.
During said switchover phase, the territorial coverage of the digital signal may undergo some discontinuity. In fact, it may happen that in a certain area a program is only received in analog format, while in another area it is only received in digital format, and in yet another area it is received in both the analog and digital formats.
In the technical terminology used in digital radio-television broadcasting, the term “service” is generally employed to indicate what in the analog world is called “program”. In this context, the term “program” is used to indicate both an analog program and a digital service.
Some television receivers currently available on the market are equipped with a dual tuner capable of receiving both radio-television signals in a first format, in particular analog television signals, and radio-television signals in a second format, in particular digital television signals.
On the other hand, radio-television receivers are also becoming widespread which are capable of receiving both cable radio-television programs transported by using the TCP/IP protocol and radio-television programs receivable through electromagnetic signals irradiated by suitable terrestrial or satellite broadcasting stations.
The term “signal format” refers herein to a signal having particular structural characteristics in terms of encoding (e.g. MPEG2, MPEG4), typology (analog or digital) and distribution (cable, satellite, terrestrial, mobile, Internet).
For the purposes of the present description, the following different radio-television signal formats will be taken into account: PAL signals, SECAM signals, NTSC signals, DVB-T signals, DVB-T2 signals, DVB-C signals, DVB-S signals, DVB-H signals, encapsulated radio-television signals broadcast on packet-switching networks, e.g. by using the IP protocol (Internet Protocol), and other types of signals, whether present or future, which differ in their encoding, typology and distribution mode.
As known, many radio-television signal receivers available on the market are fitted with systems for automatically programming the radio-television programs: analog radio-television signal receivers utilise, for example, the so-called ATSS system (Automatic Tuning and Sorting System) described in European patent no. EP 0486988, whereas digital radio-television signal receivers employ a system based on the logic channel number (LCN).
Said logic channel number, hereafter referred to as “LCN code”, is a number assigned by consortia of radio-television broadcasters to a certain program receivable in a certain geographical or catchment area.
The ATSS system allows to create an automatic procedure for searching the programs receivable in the television frequency bands of the analog signal, as well as to sort them afterwards in a predefined order independent of their transmission frequency and set at the factory on the basis of criteria common to the users in a certain catchment area, typically consisting of a national state.
Instead, the LCN is a numerical code which identifies the programs broadcast in digital terrestrial format by the various broadcasters, and is used by most digital terrestrial television receivers for the purpose of automatically assigning to each received program a predefined position in the program list.
The term “program list or table” is used in this context to indicate a sorted sequence of radio-television programs which the radio-television signal receiver can tune to, regardless of the broadcasting source and of the transmission means in use, wherein each program is associated with a particular numerical key of a keypad or remote control that can be selected by the user.
During the switchover from analog to digital, i.e. from a radio-television signal in a first format to a radio-television signal in a second format, the systems for automatically programming radio-television programs implemented in a radio-television signal receiver generate program lists subject to different destinies. In fact, as the switchover phase goes on, the analog program list will have more and more empty positions, while the digital program list will have less and less empty positions until, when the switchover is completed, the analog program list will be totally empty and therefore only the digital program list will be used.
In the future there will be a similar transition when radio-television program broadcasting gradually switches from the DVB-T system, i.e. a digital signal in a first format, to the DVB-T2 system, i.e. a digital signal in a second format.
Again, there will be a switchover phase in which it may happen that in a certain geographical area radio-television signals can be received simultaneously in a first and a second digital formats, which may or may not belong to the same radio-television stations (e.g. RAIUNO, RETE 4), so that there may be similar situations of programs existing in two different radio-television signal formats.
United States patent application US 2007/0099654 describes a television signal receiver which comprises both an analog tuner and a digital tuner, so that it can receive both analog and digital television signals. Said receiver further comprises control means which generate a table based on the logic channel number (LCN) of the digital television signal broadcast by the television station.
The table based on the logic channel number is stored by the television signal receiver into a memory, so that it can be retrieved by the receiver control means to select the program chosen by the user, e.g. BBC or MTV.
The method described in said US patent application is implemented during a scan of the frequency spectrum of the television signals receivable by the television receiver, and includes the following steps:                if a digital television signal with a logic channel number is found, then the associated program will be assigned, in the program table, the position corresponding to the logic channel number;        if a digital television signal without a logic channel number is found, then the associated program will be assigned, in the program table, the first available position or the first position available after a predetermined position;        if a digital television signal with a logic channel number is found, but the position where it should be placed is already taken by an analog program, then the associated digital program will be assigned, in the program table, the position corresponding to the logic channel number, while the analog program will be assigned the first subsequent position available in the table;        if an analog television signal is found, then the associated program will be assigned the first position available in the program table.        
However, the result of this program sorting made in accordance with said US patent application may not be liked by the user, since said result will depend on the order in which analog television signals are transmitted. Therefore, it may happen than a user accustomed to associating a certain program with one specific remote control key cannot figure out the sorting generated by the television signal receiver using the method of said US patent application.
For example, Italian users are used to associating key 1 with RAIUNO, key 2 with RAIDUE, key 3 with RAITRE, key 4 with RETE 4, key 5 with CANALE 5, key 6 with ITALIA 1, and key 7 with LA7. In those Italian regions where RAI2 and RETE 4 are only broadcast in digital format, the television signal receiver according to said US patent application will correctly place RAI2 in position 2 and RETE 4 in position 4, but it may, for example, place LA7 in the first position if that program's transmission frequency is the first one which is encountered during the automatic procedure that scans the frequency channels assigned to radio-television stations. This will confuse the user, who is accustomed to seeing at least some of the receivable programs in a certain order, thus forcing him/her to carry out a time-consuming manual procedure to put the channels back into the desired sequence.
As known, the user can also be allowed to create a list or table of favourite programs according to his/her own preferences, by combining the radio-television stations included in the program tables generated by the radio-television signal receiver according to specific sorting criteria. However, such a favourite program table must be built manually by picking the programs stored in the various radio-television program tables one by one, thus requiring a long, annoying and repetitive series of operations. Moreover, current dual-tuner receivers include two program tables associated with the two tuners, so that the user must remember not only the number, but also in which one of the two program tables the desired program has been stored. Modern receivers are typically equipped with a key for switching between the two tables, which must be pressed in order to switch from one tuner to the other, resulting in a longer switching time and more keys to be pressed to watch the desired program.
The teaching of the present invention is also applicable to this kind of receivers, thus bringing a considerable advantage to the user when selecting radio-television programs.